Microwave oven



FIG. 1 is a front view of a microwave oven showing our new design;

FIG. 2 is a rear view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a left side elevational view thereof; and,

FIG. 6 is an isometric view thereof.

The details shown in broken lines are for environmental purposes only and form no part of the claimed design. 

The ornamental design for a microwave oven, as shown and described. 